Math, asked by maya30567, 7 months ago

3
Prove that cos10° cos 30° cos 50° cos 70°
16​

Answers

Answered by YuJin743
2

hope this helps you my dear

Attachments:
Answered by kesterrajanofficial
1

Answer:

cos30.(cos50cos10).cos70

= root3/2.1/2(2cos10cos50)cos70 root3/2.1/2 (cos60 + cos40 ).cos70.. .[ bcoz 2cosxcosy

= cos(x+y) + cos(x-y)] %D %3D

= root3/4 (cos60.cos70 + cos40cos70)

= root3/8 [ cos70 + 2cos40cos70] %3D root3/8 [ cos70 + cos110 + cos30] %3D

= root3/8 [ cos70 - cos70 + root3/2] %3D root3/8. root3/2 %3D

= 3/16

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